The present invention relates to motor vehicle bumper systems.
A motor vehicle typically has a bumper bar supported on a body of the motor vehicle by energy absorbers which convert into work a fraction of the kinetic energy of a low speed impact on the bumper bar. Such bumper energy absorbers commonly include relatively moveable structural elements attached to the body and the bumper bar and a resistance medium between the structural elements. In a high speed impact, kinetic energy is converted into work by plastic deformation of body structure of the motor vehicle between a passenger compartment thereof and the point of impact. As motor vehicles have become more compact, however, the energy absorbing capability of the body structure of the motor vehicle has decreased as the span between the passenger compartment and the bumper bar has decreased.
A bumper energy absorber has been provided which supports a bumper bar close to a body of a motor vehicle except when sensors on the vehicle detect an impending impact. In that circumstance, the bumper energy absorber extends the bump bar out from the body to increase the span between the passenger compartment and the bumper bar and thereby increase the fraction of the kinetic energy of a high speed impact on the bumper bar that is converted into work. Exemplary outwardly extending bumpers are described, e.g., in U.S. Pat. No. 6,302,458, U.S. Pat. No. 5,967,573 and U.S. Pat. No. 5,370,429.
Stationary bumpers have also separately been provided with a stiffener assembly which is capable of extending downwardly. The stiffener assembly is adapted to resist a lower leg of a pedestrian from bending under the vehicle in case of an impact. An exemplary downwardly extending stiffener assembly attached to a stationary bumper is described in U.S. Pat. No. 6,089,628.
In accordance with a first aspect of the present invention a method of placing a bumper system in a pre-impact mode is provided. The method includes extending a bumper member outwardly and extending a stiffener member downwardly. Both the bumper member and the stiffener member being separately adapted to engage an object.
In accordance with another aspect of the present invention a motor vehicle bumper system is provided. The bumper system includes a bumper member movable between a retracted position and a laterally extended position. A stiffener member is movable between a retracted position and a downwardly extended position. An actuator mechanism is adapted to move the bumper member between the retracted and laterally extended positions and to cause the stiffener member to move between the retracted and downwardly extended positions as a result of moving the bumper member.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.